There are numerous types of rooms and spaces where acoustical behavior is important. They include any space where an audience will listen to a live musical performance or the spoken word, or where an audience will listen to pre-recorded audio programs. They also include more specialized spaces that are used for recording audio or for monitoring previously recorded audio material.
As a result, acoustical performance is a critical component in recording studios, recital halls and auditoriums, movie theaters, legitimate theaters, music listening rooms, home theaters, music practice rooms, houses of worship, audio and video production rooms, and a variety of other related types of facilities.
The behavior of sound within these rooms is an essential aspect of their function. That behavior depends on the volume of the enclosed space, the shape of that space, and the acoustical characteristics of the surfaces and materials within the space.
Surface treatments can affect the sound that strikes them in three ways: 1) they can reflect the sound, changing its direction of travel, 2) they can absorb the sound, which attenuates the amount of sound within the space, or 3) they can diffuse the sound, spreading out the acoustic energy over time and/or space.
The characteristic acoustical response of a surface varies with the frequency of the incident sound. For example, a surface that is almost completely absorptive to sound at 2000 Hertz (Hz) may be almost completely reflective to sound at 50 Hz. Designers, contractors, and owners of acoustical spaces select surface treatments to enhance the acoustical environment. The selection process involves determining the desired type of surface treatment, its acoustical characteristics with respect to frequency, its placement within the space, its orientation to the possible sources and receivers of sound, and its relationship to the other surfaces within the space and their respective finishes.
Surface treatments can be selected to affect specific reflection paths, or can be chosen based on their influence on the overall acoustical characteristics of the space. The application of these surface treatments may be based on correcting anomalies, or intended to create an overall balance of reflection, absorption, and diffusion for the space as a whole.
One typical surface treatment is foam products, used to cover portions of walls and ceilings. In their traditional application foam products provide broadband sound absorption. They are typically more effective at absorbing sound in the upper portion of the audible frequency range—for example, above 500 Hz—than in the lower portion. Their low-frequency performance is primarily limited by the overall thickness of the material. Foam used for sound absorption is an inexpensive treatment relative to other commercially available alternatives.
Generally, the surface shapes of commercially available foam products are limited to three types: a continuous wedge pattern, a pyramidal pattern, or an “egg crate” (rounded pyramidal or conical) pattern. Generally, these products have only been available as square or rectangular tiles, such as Auralex™ StudioFoam™, and example of the latter being shown in FIG. 17a (installed) and FIG. 17b (installed on two walls).
Consequently, foam products used as an acoustical surface treatment have had limited aesthetic appeal, partly due to their unit shape, partly due to their simple surface shapes, and partly due to the appearance of the foam material itself. In addition, commercially available foam products have had limited acoustical utility, since in their intended application they have offered only sound absorption, and have not offered any adjustability with respect to frequency response. Indiscriminate application of traditional foam products often leads to an imbalance in acoustical response, especially in presenting too much high-frequency absorption relative to low- and mid-frequency performance.
Therefore, there is a need for an acoustic material which is suitable for application to surfaces in studios, theaters, and performance halls, to selectively enhance the frequency response of the surface, and which provides an aesthetic appearance suitable for use in non-technical environments (e.g. within a private home or public performance hall). Further, there is a need in the art for these materials to be producible at a low cost with high efficiency (e.g. minimized material waste), and to be transportable via standard shipping at minimized costs.